Chronic pain, depression, and addiction represent immense health problems of epidemic proportions. The 2011 Institute of Medicine (IOM) report on Relieving Pain in America states that over 116 million Americans suffer from chronic pain with an annual price tag exceeding half a trillion dollars. Similarly, the National Institute of Mental Heath and National Institute of Drug Abuse have reported that mood disorders and addiction affect greater than 10% of the total US population. The mammalian nervous system is built from hundreds of different neuronal and glial cell types. This incredibly diverse array of cells has made dissecting brain function and treating neuropathogical states such as pain, depression, and addiction one of the most difficult challenges facing medical research. Understanding how these neural circuits communicate with one another is one of the major goals of neuroscience, and discoveries in this arena open new avenues for therapeutic intervention. As nanotechnology and materials engineering have evolved, there has been an increasing need and potential for neural micropolymeric interfaces to be developed that could be used for the study and treatment of neurological and psychiatric diseases. In this transformative research application we have assembled a multidisciplinary collaborative team between materials scientists and neurobiologists. Together we propose to: (i) Develop novel biocompatible, multimodal micro-ILED devices suitable for stable integration with the central and peripheral nervous system, (ii) use a combination of these micro-ILED devices with optogenetics to dissect the neural circuits involved in and develop treatments for neuropathic pain (iii) employ these micro-ILED devices for dissecting neural circuits and signal transduction in stress and affective disorders. In an integrated team approach, we will test, develop, and optimize this novel technology. The ultimate goal will be to develop multifunctional nanomaterial micro-ILED wireless devices for full integration with diverse neural circuits. In this project we using a combination of light-sensitive channel activation and light-activation of intracellular signal transduction cascades using engineered G-protein coupled receptors (GPCRs) within peripheral neural circuits involved in pain and central neural circuits involved in stress and negative affect including the locus ceoruleus (LC) and ventral tegemental areas (VTA). Using these novel micro-ILED devices we will dissect the heterogeneous populations of sensory nociceptors, stress, and reward neurocircuitry. Together this research will not only provide a foundation for the integration of nanoscale devices with mammalian neural circuits, but also it will guide future efforts to interface and interact with selected neural circuits in clinical settigs with respect to pain and psychiatric diseases.